Attenuation Control Device for Lithographic Beam Intensity
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Solution Overview
Problem
Current lithographic apparatuses, particularly in extreme ultraviolet (EUV) lithography, face challenges in achieving high measurement accuracy for controlling the intensity of the projection beam due to non-uniformity issues and the inability to vary the overall intensity of the radiation incident on the substrate, leading to inefficiencies and increased complexity with multiple radiation sources.
Innovation Solution
A lithographic apparatus with an attenuation control device using a common radiation source for position detection and tiltable venetian blind-like blades to adjust the radiation beam's intensity across its cross-section, allowing for precise control of the patterned radiation beam's intensity both in the scanning and transverse directions, reducing component count and thermal inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple radiation sources are used for position detection of each blade, then measurement precision is improved, but device complexity and thermal management requirements increase
Solution Approach 1:
The patent merges multiple separate radiation sources into a single common radiation source that serves all position detectors. This single source emits radiation that is distributed to multiple detectors, each detecting the position of different blades. This reduces the number of radiation sources from multiple to one, simplifying the system while maintaining the ability to detect positions of all blades accurately.
Solution Approach 2:
The single common radiation source performs multiple functions by serving all position detectors simultaneously. Instead of each detector having its own dedicated radiation source, the common source provides radiation to all detectors, making it a universal source that fulfills multiple detection functions across the entire blade array.
2Measurement precision
If multiple radiation sources are used for position detection, then measurement precision is improved, but cooling requirements and energy consumption increase
Solution Approach 1:
The patent combines multiple radiation sources into one common source, which directly reduces the total energy consumption and heat generation. Since fewer radiation sources are operating, the cooling infrastructure required is reduced proportionally, lowering the energy needed for thermal management while maintaining adequate position detection precision across all blades.
3Illumination intensity
If transmissive filter is used to correct non-uniformity, then beam uniformity is improved, but adaptability to slow variations is limited
Solution Approach 1:
The patent replaces the static transmissive filter with dynamic venetian blind blades that can be adjusted in real-time. The blades are positioned at different locations across the beam path and can be independently moved to change their attenuation positions, allowing the system to adapt to slow variations in beam uniformity over time while maintaining correction effectiveness.
Solution Approach 2:
The system changes the parameter of filter adjustability by using movable blades instead of a fixed filter. The blades can be repositioned along their respective axes to modify the attenuation profile, enabling the system to adapt to changing beam uniformity conditions while maintaining correction capability throughout the exposure duration.
4Manufacturing precision
If venetian blind blades are located closer to the reticle, then spatial frequency of correction is improved, but sharp blade edge images appear on substrate
Solution Approach 1:
The patent applies different properties to different parts of the blade system by positioning blades at specific locations across the beam path. Each blade is placed at a location optimized for its function, with the common radiation source positioned to illuminate all blades without creating sharp edge images on the substrate. This local optimization allows high spatial frequency correction while avoiding the harmful effect of sharp blade edge images.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables high-accuracy control of the radiation beam's intensity, reducing thermal drift issues, lowering component and cooling requirements, and allowing for real-time uniformity correction, thus improving the overall efficiency and reliability of the lithographic process.
Implementation Method 1
an attenuation control device for adjusting the members in such a manner as to control the attenuation of the patterned radiation beam projected onto the target portion of the substrate
Implementation Method 2
a common radiation source for generating the beams of detecting radiation for detecting the positions of the members
Data Source
AI summary
An attenuation adjustment device is disclosed that includes a plurality of members configured to cast penumbras in a radiation beam illuminating a patterning device in a lithography apparatus. Furthermore, an attenuation control device is provided to adjust the members in such a manner as to control the attenuation of the patterned radiation beam projected onto a target portion of a substrate across the cross-section of the patterned radiation beam. The attenuation control device includes a detector configured to provide an output indicative of the position of each member in dependence on detection of a beam of detecting radiation reaching the detector after attenuation by the member.